Water Balloon topic

Threads related to water balloon launchers.
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joannaardway
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Post by joannaardway » Fri Mar 03, 2006 5:58 pm

I understand that combustion is very rare in a water balloon launcher, but I had my reasons (mostly faster reloads)

However as people say it should do so, I shall switch to air pressure.

Fast fire is important to me, so I need a quicker reload. I suppose it is possible I could design one with 3 or more pressure chambers, and turn them on one at a time, into a main feed pipe, where the main trigger valve would be located. Concept picture below:

Image


The blue arrow is pointing at the three separate pressure tanks, which can be pressurized one at a time and are stacked in a "triangle".

The green arrows show the three ball valves that open the tanks one at a time.

The red arrow indicates the solenoid valve that acts as the main trigger.

The black arrow shows the direction of air flow. The launcher will obviously be in this direction (but it will almost certainly be an "over-under type" and bend back on itself). A breech loading capacity rather than muzzle loading or other types should allow me to fire three balloons in rapid succession.

I want to get really good range, so I will pressure test it at higher pressures than normal to allow me to get this better range, should I need it. (What pressure do most people use?)

I plan to have a few different "weights" of balloons for varying tasks, a bit like detailed in my last post, but obviously different.

Instead of having all the tanks at the same pressure, I could elect to put one or two at a higher pressure for longer range shots, or one at a lower pressure if I think I might need to fire at close range.

However, doing that would limit the "fast fire" capacity, meaning that a tank would be unavailable for standard fire.

What do people think of the concept? Any ideas for improvements? I won't be making this for some time, so I have plenty of time to think it over.

My final question is what does "C/B ratio" mean? - I couldn't work it out.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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Drenchenator
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Post by Drenchenator » Fri Mar 03, 2006 10:19 pm

Why combustion? Sorry if this is being blunt but combustion is the worst type of cannon you can use. I'm not talking about safety here. I'm talking about power. A combustion generates 35 PSI max. Whereas with a penumatic, you can get over 100 PSI.
Combustion is not weak at all. Pneumatic is actually the weaker of the two. Combustion creates an explosion to propel the air which then propels the projectile, while pneumatic systems just propel the air into the projectile to move it. I don't know about other people, but I would rather get hit by a bullet shot from a pneumatic gun that any combustion gun.

Most people use stock valves which makes the construction of a repeating pneumatic gun hard. I can see why someone would want to use combustion because it may be easier. But I have created the first water balloon launcher with a semi-automatic valve and trigger. So repeating pneumatic systems are not impossible to build.
have "shells" to be quick to load
From my experience with making homemade Nerf guns, I can easily say that shells do not help as much as they hurt (when dealing with shooting off darts). My semi-auto Nerf homemade (the same gun as before, different barrel assembly) uses shells and this created many problems. Ejection would be the main problem, but if you can solve this, the gun should work fine. I would just recommend against using shells, but shells will allow you to put wadding in for each shot. I have actually designed a bolt action water balloon launching assembly for my Nerf homemade, but I have never made it because I do not think it would be worth the work to build it.
My final question is what does "C/B ratio" mean? - I couldn't work it out.
C/B ratio means chamber to barrel ratio. It is the ratio between the volume of the pressure chamber and the volume of the barrel. I don't think there are any "ideal" ratios. It really depends what you want with the gun. If you want power, make the chamber large. If you want accuracy, make the barrel long.
The Drenchenator, also known as Lt. Col. Drench.

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wetmonkey442
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Post by wetmonkey442 » Sat Mar 04, 2006 3:53 pm

I'm sorry but you are completely, and inexcusably, wrong. Any high school student with a basic understanding of physics can tell you that 50 PSI of compressed air in a chamber will produce more pressure than a standard combustion chamber explosion in a chamber of the the same volume. I should know, I regularly build air cannons as a side hobby. If you doubt me, just visit any spud gun, air rifle, or antenna cannon site on the web. I'm certain Doom will back me up on this.


Drenchenator wrote:Combustion is not weak at all. Pneumatic is actually the weaker of the two. Combustion creates an explosion to propel the air which then propels the projectile, while pneumatic systems just propel the air into the projectile to move it. I don't know about other people, but I would rather get hit by a bullet shot from a pneumatic gun that any combustion gun.

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DX
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Post by DX » Sat Mar 04, 2006 4:18 pm

I'm certain Doom will back me up on this.
Doom is his brother, so I wouldn't be too sure...
I can see why someone would want to use combustion because it may be easier.
I would think that pneumatic is easier, because you can whip one up in under a half hour.
I don't think there are any "ideal" ratios.
I partially agree, but there is an ideal ratio if you want a nice balance of power and accuracy. Or you could make an insanely long one, such as the Havoc design, in order to get both.
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m15399
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Post by m15399 » Sat Mar 04, 2006 4:20 pm

I believe it's 8 to 1, not point 8. Could be wrong, though.

I'm skeptical about combustion launchers for a few reasons. One, as wetmonkey said, is the power. Two, the balloon will probably burst due to the heat created in the explosion. Combustion also makes a mess and you have to use a fan to air out the chamber.

Edit: I think I was wrong...
Last edited by m15399 on Sat Mar 04, 2006 4:32 pm, edited 1 time in total.

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wetmonkey442
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Post by wetmonkey442 » Sat Mar 04, 2006 5:16 pm

I believe it's 8 to 1, not point 8. Could be wrong, though.


I'm pretty sure it's .8:1. However, it is true that varying the ratios will produce different extremes of guns.
I can see why someone would want to use combustion because it may be easier.

Actually, although a combustion is easier to build, a pneumatic can be just as easy if not easier to pressurize. The simple use of 12gram co2 cartridges makes pressurization easy. However as Duxburian will tell you, it doesn't take much time or effort to manually pump up a pneumatic compression chamber. As long as the chamber volume in below 300 cubic inches, you can use a bike pump.

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m15399
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Post by m15399 » Sat Mar 04, 2006 5:25 pm

Woh, I totally missed the second page.

I think that combustion guns can be more powerful than a pneumatic gun of the same size if the propellant is better than hair spray. There is a topic on Spudtech in which a guy used gun powder, and got somewhere around 7000 fps. He was a mechanical engineer, so I wouldn't recommend using gun powder unless you're familiar with it.

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joannaardway
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Post by joannaardway » Sat Mar 04, 2006 7:00 pm

Well, gunpowder had crossed my mind, and I have studied enough of my a-levels to be able to work out the masses needed, but I now really like my multi pressure tank idea. And it should be a lot safer....
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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SSCBen
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Post by SSCBen » Sat Mar 04, 2006 10:18 pm

I'm sorry but you are completely, and inexcusably, wrong. Any high school student with a basic understanding of physics can tell you that 50 PSI of compressed air in a chamber will produce more pressure than a standard combustion chamber explosion in a chamber of the the same volume. I should know, I regularly build air cannons as a side hobby. If you doubt me, just visit any spud gun, air rifle, or antenna cannon site on the web. I'm certain Doom will back me up on this.
The Drenchenator and I are both taking AP Physics at the moment, so I wouldn't bring the thought of "experience" up. He even has a much better grade than I do as well, mainly because I only care about the AP exam. Regardless, most of what we do in AP Physics is simple vector math or derivative calculus, not so much projectile motion and pressure.

Sorry, but I can't back everyone up. I'll explain my thoughts below. ;)

You're confusing pressure with force here. Pressure is not force. Pressure can provide a force, but pressure is not force. Combustion does not operate on pressure as does pneumatic. Combustion creates a massive volume of hot gas that naturally does not want to compress, pushing the projectile from the barrel as it expands. In contrast, pneumatic guns are already pressurized, so once the valve is opened the gas expands, which in turn ejects the projectile. Any pressure measured from a combustion spud gun quickly dissipates just like the pressure from a pneumatic spud gun with the valve open.

If you securely plugged up the end of a combustion spud gun so the expanding gas could not exit, most plastic pipe guns would literally explode. That's because the massive volume of gas could not be contained in the pipe - too much pressure. Pressure is not force, pressure is the result of a large volume of gas in a small space. Remember, P*V = P*V. The total amount of air in a chamber is the pressure times the volume, so you can use that equation to convert between different volumes and pressures.

Both are about the same, but for size combustion would be the more powerful choice. As for whether or not I would use combustion in a water balloon launcher, I don't know yet because I only have made one water balloon launcher.

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joannaardway
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Post by joannaardway » Sat Mar 04, 2006 10:58 pm

Well, on latest thoughts, might combustion not puncture the balloon? If it didn't it could provide an incredible power to weight ratio. However, balloons are prone to popping at high temperatures.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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wetmonkey442
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Post by wetmonkey442 » Sun Mar 05, 2006 9:53 pm

Ben wrote:Both are about the same, but for size combustion would be the more powerful choice. As for whether or not I would use combustion in a water balloon launcher, I don't know yet because I only have made one water balloon launcher.

I will have to concede to someone with a higher understanding. :p However, having practical experience with tons of these things, I'm still maintaining the stance that pneumatic works better than combustion. If anything, pneumatic will give you a larger volume of air activing as force than a combustion would, because a combustion starts pushing the projectile the moment the explosion takes places. Unless, you create a hybrid launcher...Even I'm not entirely sure how those work ;) .

Good luck anyway with your project, joannaardway, and please don't hesitate to post pics!

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joannaardway
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Post by joannaardway » Sun Mar 05, 2006 10:56 pm

Well, the project isn't due to start for a few months, and I've heard that finding the stuff can prove to be difficult in the UK, so it might take a while beyond that.

However, before then, if I have blueprints or scrawled notes then I could provide links to these.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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joannaardway
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Post by joannaardway » Tue Mar 14, 2006 2:15 pm

I've being thinking of adjusting my plans, adding a section to make it a combined wbl.

I would have the three air tank design I showed a few posts back, but also a seperate combustion chamber mounted at the back of the launcher, allowing it to fire using either method.

The seperate chamber could be sealed off from the rest of the system a bit like the air tanks can, but on the other side of the solenoid valve.

It would need to have two trigger mechanisms, one to fire the combustion chamber, another to use the air tanks.

Good idea?
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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m15399
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Post by m15399 » Tue Mar 14, 2006 11:09 pm

If you aren't planning on using water balloons, ya. Great idea. The power of pneumatic with the backup of reload time of combustion.

Only problem is you are using water balloons. Combustion = Nono for water balloons. It would most likely melt/pop the balloon.

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joannaardway
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Post by joannaardway » Tue Mar 14, 2006 11:25 pm

Fine then, the design reverts.

I'd love to add rifling, but presumably this will be very hard, and will need to project inwards, because if it were cut into the tube, then I'd guess that the air would just go around the balloon. This will need a lot of thinking through.

The design has had various concepts added and removed from it. It appears that it will be a variant of a standard over-under type. I haven't decided how long it's going to be, but I'm going to make sure that it doesn't exceed a metre in length - that would be too large anyway. It will almost certainly have some form of scope.

When I've built it, I think I'll call it the Cerberus, after the three headed dog at the gates of hell (to refer to the three pressure chambers).
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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